android - Android 服务和 Activity 之间的通信

Question

我想开发一个包含三个 Activity 和两个服务的 Android 应用。

第一个名为 WebClientService 的服务使用处理程序每​​ 30 秒调用一次 REST API，并且必须将结果通知 Activity Activity 。它还必须通知名为 DatabaseService 的第二个服务，以更新本地数据库。

数据库服务只会在 Activity 的 onCreate 时调用一次(以防应用程序崩溃和重启)，并且只会在 onRestart 时调用一次(这样我们就有了数据以防出现连接问题)。然后，由于 WebClientService 每 30 秒通知一次“Activity ” Activity ， Activity 将自行更新。

问题是:

• 通知 Activity Activity 和后台数据库服务更新的最佳方式是什么？我的想法是在 WebClientService 和 BroadcastReceiver 中使用 sendBroadcast() 在每个 Activity 和 DatabaseService 中，这是正确的方法吗？

• 我应该对 AllMeetingRoomActivity 和 DatabaseService 之间的通信使用相同的方法还是应该使用 Bound Service ?

谢谢

更新:DatabaseService 将不再是后台服务，而只是 WebClientService 和 Activity 之间的数据库层的共享实例。

所以现在的问题是:将我的 30 秒更新写入本地数据库并允许 Activity 每隔几秒更新一次，只需从本地数据库读取是否是一个好方法？这会不会对性能产生太大影响？

上下文:

遵循我目前已实现的内容，但使用 SettableFutures，因此一旦我弄清楚如何使它们有效通信，就需要使用 Services 和 Broadcasts 重新实现:

public class MainActivity extends AppCompatActivity {               

    private TextView meetingsTextView;
    private EditText mEdit, editSubject;

    private final ConnectorInitializer clientInitializer = new ConnectorInitializer();
    private AppConnector genericClient; // can use OutlookClient or a test client to talk with a mock server

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        // initializes client based on the settings in "config.json"
        genericClient = clientInitializer.create(this);

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        meetingsTextView = (TextView) findViewById(R.id.NowMeeting);
        mEdit   = (EditText)findViewById(R.id.editText);
        editSubject   = (EditText)findViewById(R.id.editSubject);

        Futures.addCallback(genericClient.logon(this, scopes), new FutureCallback<Boolean>() {
            @Override
            public void onSuccess(Boolean result) {
                Log.d("APP", "-- Logged in. --");

                databaseConnector.synchronouslyGetBackupFromLocalDatabase() // FUTURE
                // callback here
                // onSuccess, onFailure

            }

            @Override
            public void onFailure(@NonNull Throwable t) {
                Log.e("\n ~~~~>> logon \n", t.getMessage());
                meetingsTextView.setText(R.string.Login_Failed);
            }
        });

    }

    /** At the moment the UI is not updated automatically every 30 seconds
    *   but manually using a refresh button
    */
    public void getBookings(@SuppressWarnings("UnusedParameters") View view){

        Log.d("APP", "Retrieve button clicked: "+(DateTime.now())+". Calling async getCalendar.");
        meetingsTextView.setText(R.string.retrieving_events);

        try{
            Futures.addCallback( genericClient.getCalendarEvents(), new FutureCallback<String>(){
                @Override
                public void onSuccess(final String resultCalendars) {

                    Log.d("APP", "Success. Result: "+resultCalendars);

                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {

                            Log.d("APP", "Calendars SUCCESSFULLY retrieved.");
                            String meetingsRetrieved = getString(R.string.calendar)+resultCalendars;
                            meetingsTextView.setText(meetingsRetrieved);

                            Toast.makeText(getApplicationContext(), "Success!", Toast.LENGTH_LONG).show();
                        }
                    });

                    databaseConnector.asyncUpdateLocalDbWithResults(); // FUTURE
                    // callback here
                    // onSuccess, onFailure

               }

                @Override
                public void onFailure(@NonNull Throwable t) {
                    Log.e( "APP", "Calendar error. Cause: "+t.getLocalizedMessage() );
                    String retrieveError = "Retrieve error. \n\n\n"+t.getLocalizedMessage();
                    meetingsTextView.setText(retrieveError);
                    Toast.makeText(getApplicationContext(), "Fail!", Toast.LENGTH_LONG).show();
                }
            });

        }catch(Exception ex){    
            Log.e("APP","Something went wrong in your code. Cause:"+ex);
        }
    }

Answer 1

最佳选择:

使用LocalBroadcastManager。更多引用here .

我的服务.java:

private LocalBroadcastManager localBroadcastManager;
private final String SERVICE_RESULT = "com.service.result";
private final String SERVICE_MESSAGE = "com.service.message";

@Override
public void onCreate() {
    super.onCreate();

   // Other stuff

   localBroadcastManager = LocalBroadcastManager.getInstance(this);
}

在服务中添加以下方法，每当您想要将数据从服务更新到 Activity 时，通过传递 Arguments 来调用方法。

private void sendResult(String message) {
    Intent intent = new Intent(SERVICE_RESULT);
    if(message != null)
        intent.putExtra(SERVICE_MESSAGE, message);
    localBroadcastManager.sendBroadcast(intent);
}

HomeActivity.java:

private BroadcastReceiver broadcastReceiver;

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    super.setContentView(R.layout.activity_home);
    broadcastReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String s = intent.getStringExtra(MyService.SERVICE_MESSAGE);
            // do something here.
        }
    };
}

@Override
protected void onStart() {
    super.onStart();
    LocalBroadcastManager.getInstance(this).registerReceiver((broadcastReceiver), 
        new IntentFilter(MyService.SERVICE_RESULT));
}

@Override
protected void onStop() {
    LocalBroadcastManager.getInstance(this).unregisterReceiver(broadcastReceiver);
    super.onStop();
}

希望对您有所帮助。